Borrowings and Contractual Commitments Borrowings and Contractual Commitments - Additional Information (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
time deposits $250,000 or more		$ 1,700	$ 1,400
Long-term Debt	[1]	11,748	8,462
Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Long-term Debt		2,800	408
Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt	[2]	6,798	3,690
Parent Company [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 4,950	$ 4,772

[1] Includes debt of consolidated VIEs of $222 million and $259 million at December 31, 2016 and December 31, 2015, respectively.

[2] 88% and 81% of total subsidiary debt was issued by the Bank as of December 31, 2016 and 2015, respectively.